Flux-switch motor topologies employ a stator having permanent magnets and coils through which alternating current is applied, and an interior rotor composed of or including magnetically permeable material. When alternating current is applied to the coils of the stator, the variation in magnetic flux in the stator generates a torque on the rotor.
In large direct drive applications, because of the relatively high cost of magnets and mounting provisions for them, there is an interest in minimizing the amount of magnetic material being used in construction of the motor as well as how the magnets are mounted. In certain applications, even though the motion requirements in terms of torque or power may not demand it, particularly with regard to large permanent magnet motors, the geometry of the motor itself requires that the magnetic materials subtend the entire 360 degrees of rotation, resulting in the use of greater volumes of permanent magnets than necessary and requiring costly mounting provisions. This leads to increased cost, weight and complexity of the motor device.